Explore the vast range of titles available.

The design of cyber-physical systems (CPS) is challenging due to the heterogeneity of software and hardware components that operate in uncertain environments (e.g., fluctuating workloads), hence they are prone to performance issues. Software performance antipatterns could be a key means to tackle this challenge since they recognize design problems that may lead to unacceptable system performance. This manuscript focuses on modeling and analyzing a variegate set of software performance antipatterns with the goal of quantifying their performance impact on CPS. Starting from the specification of eight software performance antipatterns, we build a baseline queuing network performance model that is properly extended to account for the corresponding bad practices. The approach is applied to a CPS consisting of a network of sensors and experimental results show that performance degradation can be traced back to software performance antipatterns. Sensitivity analysis investigates the peculiar characteristics of antipatterns, such as the frequency of checking the status of resources, that provides quantitative information to software designers to help them identify potential performance problems and their root causes. Quantifying the performance impact of antipatterns on CPS paves the way for future work enabling the automated refactoring of systems to remove these bad practices.

Although sound performance analysis theories and techniques exist, they are not widely used because they require extensive expertise in performance modeling and measurement. The overall goal of our work is to make performance modeling more accessible by automating much of the modeling effort. We have proposed a model interoperability framework that enables performance models to be automatically exchanged among modeling (and other) tools. The core of the framework is a set of model interchange formats (MIF): a common representation for data required by performance modeling tools. Our previous research developed a representation for system performance models (PMIF) and another for software performance models (S-PMIF), both based on the Queueing Network Modeling (QNM) paradigm. In order to manage the research scope and focus on model interoperability issues, the initial MIFs were limited to QNMs that can be solved by efficient, exact solution algorithms. The overall model interoperability approach has now been demonstrated to be viable. This paper broadens the scope of PMIF and S-PMIF to represent models that can be solved with additional methods such as analytical approximations or simulation solutions. It presents the extensions considered, describes the extended meta-models, and provides verification with examples and a case study.

An extension to the Performance Model Interchange Format (PMIF+) to move models among tools has been recently introduced. The original PMIF was limited to models solvable with efficient, exact solution methods such as mean value analysis and product form solutions. The extensions allow models with features that require simulation or analytical approximation solutions, such as passive resources, workloads that fork into multiple concurrent workloads, etc. This paper presents a tool for the automated transformation from PMIF+ to Qnap, and explains some of the challenging transformations required by the new PMIF+ features.

Software performance engineering (SPE) provides an approach to constructing systems to meet performance objectives. The authors illustrate the application of SPE to an example with some real-time properties and demonstrate how to compare performance characteristics of design alternatives. They show how SPE can be integrated with design methods and demonstrate that performance requirements can be achieved without sacrificing other desirable design qualities such as understandability, maintainability, and reusability.< >

The general principles for formulating software requirements and designs that meet response-time goals are reviewed. The principles are related to the system performance parameters that they improve, and thus their application may not be obvious to those whose speciality is system architecture and design. The author addresses the designer's perspective and illustrates how these principles apply to typical design problems. The examples illustrate requirements and design of: communication, user interfaces, information storage, retrieval and update, information hiding, and data availability. Strategies for effective use of the principles are described.< >

It is possible to design object-oriented systems that have adequate performance and exhibit the other qualities, such as reusability, maintainability, and modifiability, that have made object-oriented development (OOD) so successful. However, doing this requires careful attention to performance goals throughout the life cycle. The use of a performance modeling tool that supports the Software Performance Engineering process is described, for early life cycle evaluation of object-oriented systems. The evaluation of object-oriented software is illustrated with a simple example. Object-oriented methods will likely be the preferred design approach of the future. SPE techniques are vital to ensure that these systems meet performance requirements.

In an extension of the pivotal randomized trial showing vaccine efficacy, approximately 10,000 adults who had received two doses of BNT162b2 were assigned to receive a third dose or placebo. Local reactions were common but mild and transient. During a median follow-up of 2.5 months, SARS-CoV-2 was identified in 6 participants in the vaccine group and in 123 in the placebo group, for a vaccine efficacy of 95.3%.